The 140DZ has a very broad HS needle as you said. You should run it toward the leaner side of the range...maybe 1-1/3 to 1.5 open. If its rich in the middle then you can lean the pump slightly. Say 1/8th turn CCW on the pump screw.

I don't know that its a bad pump.

Turning a 16-12 at 8800 on 30% DZ fuel not down on power. I used the APC 16-12 at it turned about 8600-8800 on 30% heli. So you are in the right range.

If your pump was bad it would not idle well.

It could be cutting in the air from too rich....also when was the last time you changed the plug?
This can show similar problems. rich mid rnage and dead sticks....

Change the plug first then look to leaning the pump a little. If it gets detonation in the middle and gets that hollow sound then cut it off and richen the pump back up.

Troy Newman
Team YS